Wednesday, February 06, 2008

Researchers at McMaster University, in Ontario, say that they have grown light-absorbing nanowires made of high-performance photovoltaic materials on thin but highly durable carbon-nanotube fabric. They've also harvested similar nanowires from reusable substrates and embedded the tiny particles in flexible polyester film. Both approaches, they argue, could lead to solar cells that are both flexible and cheaper than today's photovoltaics.

Each nanowire is 10 to 100 nanometers wide and up to five microns long. Their length maximizes absorption, but their nanoscale width permits a much freer movement and collection of electrons.

LaPierre says that the aim is to produce flexible, affordable solar cells composed of Group III-V nanowires that, within five years, will achieve a conversion efficiency of 20 percent. Longer term, he says, it's theoretically possible to achieve 40 percent efficiency, given the superior ability of such materials to absorb energy from sunlight and the light-trapping nature of nanowire structures. By comparison, current thin-film technologies offer efficiencies of between 6 and 9 percent.